Semiconductor memory device and method for selecting multiple word lines in a semiconductor memory device

ABSTRACT

A semiconductor memory device that reduces the time for conducting a multiple word line selection test and operates stably. The semiconductor memory device includes memory cell blocks, row decoders, sense amps, block control circuits, and sense amp drive circuits. Each block control circuit generates a reset signal. The reset signal is used to select the word lines with the row decoders at timings that differ between the blocks. Each block control circuit provides the reset signal to the associated row decoder. The block control circuit also provides the reset signal to the associated sense amp drive circuit so that the sense amps are inactivated at timings that differ between the blocks.

This is a Division application Ser. No. 09/994,611 filed Nov. 28, 2001,now U.S. Pat. No. 6,543,431. The disclosure of the prior application(s)is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor memory device, and moreparticularly, to a method for testing for interference between adjacentcells that reduces time and prevents noise.

An adjacent cell interference test is conducted on semiconductordevices, especially DRAMs. During the adjacent cell interference test, acertain word line remains selected for a predetermined time, and a senseamplifier amplifies the cell information read from a bit line. Then,interference is detected from the cell information stored in a memorycell connected to the adjacent word line.

Due to the increase in the memory capacity of semiconductor memorydevices, the number of word lines has increased. This has lengthened thetime required to conduct the adjacent cell interference test. To savetesting costs, it is required that the testing time be reduced.Therefore, a multiple word line selection test is conducted tosimultaneously activate a plurality of word lines. In this test, it isrequired that the number of simultaneously selected word lines beincreased and abnormal functioning caused by noise be prevented.

FIG. 1 is a circuit diagram of a memory cell array and its peripheralcircuits in a semiconductor memory device (DRAM) 50. The memory cellarray has four memory cell blocks BL0, BL1, BL2, BL3. Sense amp groups 1and row decoders 2 are adjacent to the blocks BL0-BL3. Each sense ampgroup 1 includes a plurality of sense amps 8.

The peripheral circuits include sense amp drive circuits 3, blockcontrol circuits 4, a timing signal generation circuit 5, a blockaddress buffer 6, and an address buffer 7. The sense amp drive circuits3 are each associated with one of the sense amp groups 1. The blockcontrol circuits 4 are each associated with one of the blocks 0-3.

The sense amp drive circuits 3 and the block control circuits 4 receivea timing signal from the timing signal generation circuit 5. The blockcontrol circuits 4 receive a block address signal Bad from an externaldevice via the block address buffer 6.

The block control circuits 4 generate a word line set signal WLst, whichactivates word lines, and a word line reset signal WLrs, whichinactivates word lines. Further, the block control circuits 4 providethe associated row decoders 2 with the set signal WLst and the resetsignal WLrs.

Based on the timing signal and the block address signal Bad, the blockcontrol circuits 4 generate a block selection signal Bs1 and provide theassociated sense amp drive circuits 3 with the block selection signalBs1. Based on the block selection signal Bs1, the sense amp drivecircuits 3 provide the associated sense amp groups 1 with sense ampdrive signals PSA, NSA.

The row decoders 2 receive a word line address signal WLad from anexternal device via the address buffer 7. The row decoders 2 select wordlines based on the word line address signal WLad and the word line setsignal WLst and terminates the selection of word lines based on the wordline reset signal WLrs.

FIG. 2 is a diagram showing the memory cell array and its peripheralcircuits in a single memory cell block. The memory cell block includes,for example, 128 word lines WL0-WL127. A plurality of sense amps 8 areconnected to bit lines BL, which intersect each of the word linesWL0-WL127.

In response to the block selection signal Bs1 received from the blockcontrol circuit 4, the sense amp drive circuit 3 provides each sense amp8 with the sense amp drive signals PSA, NSA.

The row decoders 2 select word lines in response to the word lineaddress signal WLad and the word line set signal WLst, which areprovided in response to the word lines WL0-WL127. Further, in responseto the word line reset signal WLrs, the row decoders 2 terminates theselection of word lines.

The block control circuits 4, the sense amp drive circuits 3, and therow decoders 2 will now be discussed with reference to FIG. 3.

Each block control circuit 4 includes a block selection circuit 9, aword line set signal generation circuit 10, and a word line reset signalgeneration circuit 11. The block selection circuit 9 receives the blockaddress signal Bad at a high level and a block set timing signal Bstt ata high level. The timing signal Bstt is received from the timing signalgeneration circuit 5. The block selection circuit 9 has a latch circuit12 a and two inverter circuits 13 a to generate the block selectionsignal Bs1 at a high level in response to the block address signal Badand the high timing signal Bstt.

When the block selection circuit 9 receives a high block reset timingsignal Brst from the timing signal generation circuit 5, the latchcircuit 12 a and the inverter circuits 13 a generate the block selectionsignal Bs1 at a low level.

The word line set signal generation circuit 10 includes a NAND circuit14 a and an inverter circuit 13 b. The NAND circuit 14 a has a firstinput terminal, which receives the block selection signal Bs1, and asecond input terminal, which receives a word line set timing signalWLstt from the timing signal generation circuit 5. The inverter circuit13 b receives the output signal of the NAND circuit 14 a and generatesthe word line set signal WLst.

When the word line set signal generation circuit 10 receives the blockselection signal Bs1 at a high level and the word line set timing signalWLstt at a high level, the word line set signal generation circuit 10generates the word line set signal WLst at a high level.

The word line reset signal generation circuit 11 includes a NAND circuit14 b and inverter circuits 13 c, 13 d. The NAND circuit 14 b has a firstinput terminal, which receives the block selection signal Bs1, and asecond input terminal, which receives a word line reset timing signalWLrst from the timing signal generation circuit 5 via the invertercircuit 13 c. The two inverter circuits 13 d receive the output signalof the NAND circuit and generate the word line reset signal WLrs.

When the word line reset signal generation circuit 11 receives the blockselection signal Bs1 at a high level and the word line reset timingsignal WLrst at a low level, the word line reset signal generationcircuit 11 generates the word line reset signal WLrs at a low level. Theword line reset signal generation circuit 11 generates the word linereset signal WLrs at a high level when such signals are not received.

The sense amp drive circuit 3 includes a NAND circuit 14 c, invertercircuits 13 e, 13 f, and transistors Tr1-Tr4. The NAND circuit 14 c hasa first input terminal, which receives the block selection signal Bs1,and a second input terminal, which receives a sense amp timing signalSAt from the timing signal generation circuit 5.

The output signal of the NAND circuit 14 c is provided to the gates ofthe p-channel MOS transistor Tr1 and the n-channel MOS transistors Tr2,Tr3 via the two inverter circuits 13 e. The output signal of theinverter circuit 13 e is provided to the gate of the n-channel MOStransistor Tr4 via the inverter circuit 13 f.

The transistors Tr1-Tr4 are connected in series between power suppliesVcc and Vss. A sense amp drive signal PSA is generated at a node of thetransistors Tr1, Tr2. A sense amp drive signal NSA is generated at anode of the transistors Tr3, Tr4. A node of the transistors Tr2, Tr3 issupplied with precharge voltage Vp.

When the NAND circuit 14C receives the block selection signal Bs1 at ahigh level and the sense amp timing signal SAt at a high level, thetransistors Tr1, Tr4 are activated and the transistors Tr2, Tr3 areinactivated. This generates the sense amp drive signal PSA at a voltagethat is substantially the same as that of the power supply Vcc and thesense amp drive signal NSA at a voltage that is substantially the sameas that of the power supply voltage Vss.

When either the block selection signal Bs1 or the sense amp timingsignal SAt goes low, the transistors Tr1, Tr4 are inactivated and thetransistors Tr2, Tr3 are activated. This generates the sense amp drivesignals PSA, NSA at a voltage that is the same as the precharge voltageVp.

When the row decoder 2 receives the world line set signal WLst at a highlevel and the word line address signal WLad at a high level, the rowdecoder 2 generates a word line selection signal WL at a high level bymeans of a latch circuit 12 b and two inverter circuits 13 g. When therow decoder 2 receives the word line reset signal WLrs at a high level,the output terminal of the latch circuit 12 b goes low. In this state,the row decoder 2 generates the word line selection signal WL at a lowlevel by means of the inverter circuit 13 g.

The operation of the block control circuit 4, the row decoder 2, and thesense amp drive circuit 3 will now be discussed with reference to FIG.4.

The block set timing signal Bstt is a pulse signal. The block resettiming signal Brst goes low before the first pulse of the block settiming signal Bstt. Further, the block reset timing signal Brst goeshigh after the word line reset timing signal WLrst goes high.

If the block set timing signal Bstt goes high when the block selectioncircuit 9 is provided with the block address signal Bad, which selectsone of the blocks BL0-BL3, the block selection signal Bs1 goes high.

When the block selection signal Bs1 goes high and the word line setsignal generation circuit 10 is provided with a word line set timingsignal WLstt, which is a pulse signal, the word line set signalgeneration circuit 10 generates the word line set signal WLst, which isa pulse signal.

In the word line reset signal generation circuit 11, the word line resettiming signal WLrst goes low before the first pulse of the word line settiming signal WLstt and goes high when the word line selection signal WLgoes low. The word line reset signal WLrs goes high when the word linereset timing signal WLrst goes high.

The sense amp timing signal SAt goes high after a predetermined timefrom when the word line set timing signal WLstt goes high and goes lowafter a predetermined time from when the word line reset timing signalWLrst goes high.

If the sense amp timing signal SAt goes high when the sense amp drivecircuit 3 receives the block selection signal Bs1 at a high level, thesense amp drive circuit 3 outputs the sense amp drive signals PSA, NSA.When the sense amp timing signal SAt goes low, the sense amp drivesignals PSA, NSA shift to the precharge voltage Vp and inactivate theassociated sense amps 8.

The word line address signal WLad goes high every predetermined time.Each time the word line address signal WLad goes high, a pulse of theword line set signal WLst is provided to the row decoder 2.

The voltage of the word line WL corresponding to the word line addresssignal WLad goes high when the word line set signal WLst goes high. Thevoltage of each word line WL goes low when the word line reset signalWLrs goes high.

A first example of the adjacent cell interference test conducted on theprior art semiconductor memory device 50 will now be discussed withreference to FIG. 5.

Subsequent to a test mode entry command, the semiconductor memory device50 is provided with an active command every predetermined time. Insynchronism with each active command, the semiconductor memory device 50is provided with the word line address signal WLad and the block addresssignal Bad. Based on the operation of the block control circuit 4, therow decoder 2 selects a word line and the sense amp drive circuit 3activates a sense amp.

Referring to FIG. 5, for example, block BL0 is selected. Further, eachactive command selects every eight word lines in a manner such as WL0,WL8, and WL16.

The sense amp drive signals PSA, NSA simultaneously provide all of thesense amps 8 in block BL0 after a predetermined time from when word lineWL0 is selected. A memory cell connected to the selected word lineprovides the bit lines with cell information. Each sense amp 8 amplifiesthe cell information. This state is maintained for a predetermined time.

Then, after a predetermined time elapses, the word line reset timingsignal WLrst, which is based on the precharge command, is provided tothe word line reset signal generation circuit 11 and the selected wordlines are simultaneously inactivated. The sense amp timing signal SAtinactivates the sense amps 8. In this state, it is checked whether theactivation of the word line caused interference between adjacent cells.

Subsequently, in response to the active command, every eight word linesin block BL0 are selected sequentially in a manner such as WL1, WL9, andWL17. In this state, the sense amp drive signals PSA, NSA aresimultaneously provided to all of the sense amps 8 in block BL0 after apredetermined time from when the sense amp drive signals PSA, NSA selectword line WL1. The sense amps 8 amplify the cell information provided tothe bit line and maintain the amplified state for a predetermined time.

Such operation is repeated until all of the word lines in the block BL0are selected. Further, the same operation is performed in blocksBL1-BL3.

In this case, multiple word lines are simultaneously selected. Thus, incomparison to when the word lines are activated one by one, the testtime is reduced. However, although multiple word lines aresimultaneously selected in each of blocks BL0-BL3 in the first example,word lines of multiple blocks cannot be simultaneously selected. As aresult, test time cannot be sufficiently reduced.

A second prior art example of the adjacent cell interference test willnow be discussed with reference to FIG. 6. In the second prior artexample, multiple word lines of multiple blocks, for example, blocks BL0and BL2, are simultaneously selected. Further, multiple word lines ofblocks BL1 and BL3 are simultaneously selected. This reduces test time.

In synchronism with the first two active commands following the testmode entry command, the semiconductor memory device 50 is sequentiallyprovided with the block address signal Bad, which selects the blocksBL0, BL2. Blocks BL0, BL2 are selected based on the block address signalBad. The word line address signal WLad first selects the word line WL0continuously for two times and then selects every eight word lines in amanner such as WL8, WL16.

The first two active commands sequentially activate word lines WL0 ofblocks BL0, BL2. Subsequently, every eight word lines of blocks BL0, BL2are sequentially and simultaneously selected. The sense amps 8 of blocksBL0, BL2 are activated after a predetermined time from the selection ofword line WL0 in block BL2. The activated state is maintained for apredetermined time.

Then, the selected word lines are simultaneously inactivated in responseto the precharge command. The sense amps 8 are also inactivated.

The operation performed by the block control circuit 4, the sense ampdrive circuit 3, and the row decoder 2 to conduct the adjacent cellinterference test of FIG. 6 will now be discussed with reference to FIG.7.

In the operation of FIG. 7, the block address signal Bad is sequentiallyprovided to sequentially select blocks BL0, BL2, and the block settiming signal Bstt sequentially selects blocks BL0, BL2.

The word line address signal WLad, which selects word line WL0, isprovided for two cycles so that word line WL0 is selected in blocks BL0,BL2. The other operations, which the blocks undergo, are performed inthe same manner as the first example.

In the second example, multiple word lines of multiple blocks aresimultaneously selected. This further shortens the test time from thatof the first example. However, when the word lines are selected, manysense amps are simultaneously activated in multiple blocks. Further,when selected word lines become no longer selected, many sense amps aresimultaneously inactivated. The activation and inactivation of the senseamps produces a switching noise in the power supply. The switching noisemay cause the semiconductor memory device 50 to function erroneously.

The timing for activating sense amps is the same in the blocks. However,the timing for starting the selection of word lines differs between theblocks. This results in a shortcoming in that the margin for amplifyingthe sense amps is not constant. In other words, time t1, which isrequired to activate the sense amps 8 after word line WL0 is selected inblock BL0, is longer than time t2, which is required to activate thesense amps 8 after word line WL0 is selected in block BL2.

Thus, the margin for amplifying the cell information when word line WL0is activated in block BL0 decreases. This problem occurs becausemultiple blocks are operated at the same timing.

In other words, in the second prior art example, the block addresssignal Bad and the word line address signal WLad are provided tosimultaneously select multiple word lines in multiple blocks. Further,the sense amps are activated and inactivated at the same timing.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a semiconductormemory device that reduces the time for conducting a word line multipleselection test and functions stably.

To achieve the above object, the present invention provides asemiconductor memory device including a plurality of memory cell blocks.Each of the memory cell blocks includes a plurality of memory cells anda plurality of word lines connected to the memory cells. A plurality ofrow decoders are connected to the plurality of memory cell blocks. Eachof the row decoders selects one of the word lines in an associated oneof the memory cell blocks. A plurality of sense amp groups are connectedto the plurality of memory cell blocks. Each of the sense amp groupsamplifies cell information read from the plurality of memory cells of anassociated one of the memory cell blocks. A plurality of block controlcircuits connected to the plurality of row decoders. Each of the blockcontrol circuits simultaneously selects multiple word lines in anassociated one of the memory cell blocks and generates a sense ampcontrol signal. A plurality of sense amp drive circuits are connected tothe plurality of block control circuits and the plurality of sense ampgroups. Each of the sense amp drive circuits selectively activates anassociated one of the sense amp groups based on the sense amp controlsignal of the associated one of the block control circuits. Each of theblock control circuits generates at least one reset signal and providesthe reset signal to an associated one of the row decoders and to anassociated one of the sense amp drive circuits. The reset signal isprovided to the associated one of the row decoders so that the timingfor selecting the word lines with the row decoders differs between eachblock. The reset signal is provided to the associated one of the senseamp drive circuits so that inactivation of the plurality of sense ampgroups differs between each block.

A further perspective of the present invention is a method forconducting a multiple word line selection test on a semiconductor memorydevice provided with a plurality of memory cell blocks, which include afirst memory cell block and a second memory cell block. Each of thememory cell blocks has a plurality of memory cells and a plurality ofword lines connected to the memory cells. A plurality of sense ampgroups are connected to the first and second memory cell blocks. Each ofthe sense amp groups amplifies cell information read from the pluralityof memory cells of an associated one of the memory cell blocks. Themethod includes a first step for activating one of the plurality of wordlines in the first memory cell block and activating the sense amp groupassociated with the first memory cell block after a predetermined time,a second step for activating word lines other than the one that has beenactivated in the first memory cell block, a third step for activatingone of the plurality of word lines in the second memory cell block andactivating the sense amp group associated with the second memory cellblock after a predetermined time, and a fourth step for activating wordlines other than the one that has been activated in the second memorycell block. The third and fourth steps are performed while the first andsecond steps are continuously performed or the second and fourth stepsare performed while the first and third steps are continuouslyperformed.

A further perspective of the present invention is a method forconducting a multiple word line selection test on a semiconductor memorydevice provided with a plurality of memory cell blocks, which include afirst memory cell block and a second memory cell block. Each of thememory cell blocks have a plurality of memory cells and a plurality ofword lines connected to the memory cells. A plurality of sense ampgroups are connected to the first and second memory cell blocks. Each ofthe sense amp groups amplifies cell information read from the pluralityof memory cells of an associated one of the memory cell blocks. Themethod includes a first step for inactivating multiple word lines in thefirst memory cell block and the sense amp group associated with thefirst memory cell block, and a second step for inactivating multipleword lines in the second memory cell block and the sense amp groupassociated with the second memory cell block after performing the firststep.

A further perspective of the present invention is a method forconducting a multiple word line selection test on a semiconductor memorydevice provided with a plurality of memory cell blocks, which include afirst memory cell block and a second memory cell block. Each of thememory cell blocks have a plurality of memory cells and a plurality ofword lines connected to the memory cells, and a plurality of sense ampgroups connected to the first and second memory cell blocks. Each of thesense amp groups amplifies cell information read from the plurality ofmemory cells of an associated one of the memory cell blocks. The methodincludes a first step for activating one of the plurality of word linesin the first memory cell block and activating the associated one of thesense amp groups with the first memory cell block after a predeterminedtime, a second step for activating word lines other than the one thathas been activated in the first memory cell block, a third step foractivating one of the plurality of word lines in the second memory cellblock and activating the sense amp group associated with the secondmemory cell block after a predetermined time, a fourth step foractivating word lines other than the one that has been activated in thesecond memory cell block, a fifth step for inactivating multiple wordlines in the first memory cell block and the sense amp group associatedwith the first memory cell block, and a sixth step for inactivatingmultiple word lines in the second memory block and the sense amp groupassociated with the second memory block after performing the fifth step.The third and fourth steps are performed while the first and secondsteps are continuously performed or the second and fourth steps areperformed while the first and third steps are continuously performed.

A further perspective of the present invention provides a semiconductormemory device including a plurality of memory cell blocks. Each of thememory cell blocks includes a plurality of memory cells and a pluralityof word lines connected to the memory cells. A plurality of row decodersare connected to the plurality of memory cell blocks. Each of the rowdecoders selects one of the word lines in an associated one of thememory cell blocks. A plurality of sense amp groups are connected to theplurality of memory cell blocks. Each of the sense amp groups amplifiescell information read from an associated one of the memory cells. Aplurality of block control circuits are connected to the plurality ofrow decoders. Each of the block control circuits simultaneously selectsmultiple word lines in an associated one of the memory cell blocks andgenerates a sense amp control signal. A plurality of sense amp drivecircuits are connected to the plurality of block control circuits andthe plurality of sense amp groups. Each of the sense amp drive circuitsselectively activates an associated one of the sense amp groups based onthe sense amp control signal of the associated one of the block controlcircuits. Each of the sense amp drive circuits includes a latch circuit.

Other aspects and advantages of the present invention will becomeapparent from the following description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best beunderstood by reference to the following description of the presentlypreferred embodiments together with the accompanying drawings in which:

FIG. 1 is a schematic block diagram of a prior art semiconductor memorydevice having a plurality of memory cell blocks;

FIG. 2 is a schematic block diagram of one block in the semiconductormemory device of FIG. 1;

FIG. 3 is a schematic circuit diagram of peripheral circuits in thesemiconductor memory device of FIG. 1;

FIG. 4 is a combined timing and waveform chart illustrating theoperation performed in a first test example of the semiconductor memorydevice of FIG. 1;

FIG. 5 is a combined timing and waveform chart illustrating theoperation performed in the first test example of the semiconductormemory device of FIG. 1;

FIG. 6 is a combined timing and waveform chart illustrating theoperation performed in a second test example of the semiconductor memorydevice of FIG. 1;

FIG. 7 is a combined timing and waveform chart illustrating theoperation performed in the second test example of the semiconductormemory device of FIG. 1;

FIG. 8 is a schematic block diagram of a semiconductor memory deviceaccording to a first embodiment of the present invention;

FIG. 9 is a schematic circuit diagram of peripheral circuits of thesemiconductor memory device of FIG. 8;

FIG. 10 is a combined timing and waveform chart illustrating theoperation performed in the semiconductor memory device of FIG. 8;

FIG. 11 is a combined timing and waveform chart illustrating theoperation performed in the semiconductor memory device of FIG. 8;

FIG. 12 is a combined timing and waveform chart illustrating theoperation performed in a semiconductor memory device according to asecond embodiment of the present invention;

FIG. 13 is a combined timing and waveform chart illustrating theoperation performed in a semiconductor memory device according to thesecond embodiment of the present invention; and

FIG. 14 is a circuit diagram showing a further example of a sense ampdrive circuit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings, like numerals are used for like elements throughout.

First Embodiment

FIG. 8 is a schematic block diagram of a semiconductor memory device 100according to a first embodiment of the present invention. Thesemiconductor memory device 100 includes four memory cell blocks BL0,BL1, BL2, BL3, a plurality of sense amp groups 1, a plurality of blockcontrol circuits 21, a plurality of sense amp drive circuits 22, and aplurality of row decoders 23.

Each of the blocks BL0-BL3 is connected to the associated sense ampgroups 1 and row decoder 23.

Each of the row decoders 23 selects word lines in the associated one ofthe blocks BL0-BL3. Each of the sense amp groups 1 has a plurality ofsense amps 8. Each sense amp 8 amplifies cell information read when aword line is selected. Each of the block control circuits 21 has amultiple word line selection function, which simultaneously selectsmultiple word lines in multiple blocks.

Each of the sense amp drive circuits 22 controls the activation andinactivation of the associated sense amps 8 based on the output signalof the associated block control circuit 21.

Each of the block control circuits 21 provides the associated rowdecoder 23 with a reset signal WLrs to inactivate word lines at timingsdiffering between blocks. Further, each block control circuit 21generates a signal Ø (WLrs) to inactivate the associated sense amps 8 attimings differing between blocks and provides the signal Ø to theassociated one of the sense amp drive circuits 22.

FIG. 9 is a schematic circuit diagram of the block control circuit 21,the sense amp drive circuit 22, and the row decoder 23. Although theblock control circuits 21 and the sense amp drive circuits 22 of thesemiconductor memory device 100 differ from the block control circuits 4and the sense amp drive circuits 3, the configuration of the remainingparts of the semiconductor memory device 100 is the same as that of theprior art semiconductor memory device 50.

Each block control circuit 21 includes a block selection circuit 24, aword line set signal generation circuit 25, and a word line reset signalgeneration circuit 26. The block selection circuit 24 has a resetterminal to receive the block address signal Bad. The remaining parts ofthe block selection circuit 24 are the same as corresponding parts ofthe block selection circuit 9.

The block address signal Bad is provided in parallel to the block resettiming signal Brst. Accordingly, when the block selection circuit 24receives the block address signal Bad at a high level and the blockreset timing signal Brst, the block selection circuit 24 generates theblock selection signal Bs1 at a low level.

The configuration of the word line set signal generation circuit 25 isthe same as that of the word line set signal generation circuit 10 inthe prior art example of FIG. 3.

The word line reset signal generation circuit 26 includes a NAND circuit14 d in lieu of the inverter circuit 13 c of the word line reset signalgeneration circuit 11 of FIG. 3. The NAND circuit 14 d has a first inputterminal, which is provided with the word line reset timing signalWLrst, and a second input terminal, which is provided with the blockaddress signal Bad. The output signal of the NAND circuit 14 d isprovided to the second input terminal of the NAND circuit 14 b.Accordingly, when the word line reset signal generation circuit 26receives the word line reset timing signal WLrst at a high level and theblock address signal Bad at a high level, the word line reset signalgeneration circuit 26 generates the word line reset signal WLrs at ahigh level.

Each sense amp drive circuit 22 includes NAND circuits 14 e, 14 f, 14 g,14 h and an inverter circuit 13 h in lieu of the NAND circuit 14 c andthe inverter circuit 13 e of the sense amp drive circuit 3 of FIG. 3.

The NAND circuit 14 e has a first input terminal, which receives theblock selection signal Bs1, and a second input terminal, which receivesa sense amp set timing signal SAstt from the timing signal generationcircuit 5. The NAND circuit 14 f has a first input terminal, which isprovided with the word line reset signal WLrs, and a second inputterminal, which is provided with a sense amp reset timing signal SArstfrom the timing signal generation circuit 5.

The output signal of the NAND circuit 14 e is provided to a first inputterminal of the NAND circuit 14 g. The output signal of the NAND circuit14 f is provided to a first input terminal of the NAND circuit 14 h. Theoutput signal of the NAND circuit 14 g is provided to a second inputterminal of the NAND circuit 14 h. The output signal of the NAND circuit14 h is provided to a second input terminal of the NAND circuit 14 g.The NAND circuit 14 g, 14 h form a latch circuit.

The output signal of the NAND circuit 14 g is provided to the gates ofthe transistors Tr1, Tr2, Tr3 via the inverter circuit 13 h, and theoutput signal of the inverter circuit 13 h is provided to the gate ofthe transistor Tr4 via the inverter circuit 13 f. The transistorsTr1-Tr4 have the same configuration as those of the sense amp drivecircuit 3.

When the NAND circuit 14 e receives the block selection signal Bs1 at ahigh level and the sense amp set timing signal SAstt at a high level,the NAND circuit 14 e generates a low output signal. The NAND circuit 14g provides the inverter circuit 13 h with a high output signal. In thisstate, the transistors Tr1, Tr4 are activated and the transistors Tr2,Tr3 are inactivated. As a result, the sense amp drive circuit 22provides the associated sense amps 8 with the sense amp drive signalPSA, the voltage of which is substantially the same as that of the powersupply Vcc, and the sense amp drive signal NSA, the voltage of which issubstantially the same as that of the power supply Vss.

When the NAND circuit 14 f receives the word line reset signal WLrs at ahigh level and the sense amp reset timing signal SArst at a high level,the NAND circuit 14 f generates a low output signal. Based on the lowoutput signal of the NAND circuit 14 f, the NAND circuit 14 h outputs ahigh output signal.

In this state, the output signal of the NAND circuit 14 e is high. Thus,the NAND circuit 14 g generates a low output signal and provides the lowoutput signal to the inverter circuit 13 h. Accordingly, the high outputsignal of the inverter circuit 13 h inactivates the transistors Tr1, Tr4and activates the transistors Tr2, Tr3. As a result, the sense amp drivecircuit 22 provides the associated sense amps 8 with the sense amp drivesignals PSA, NSA, the voltage of which is the same as that of theprecharge voltage Vp.

The configuration of each row decoder 23 is the same as that of the rowdecoder 2 of FIG. 3.

The operation of the block control circuit 21, the sense amp drivecircuit 22, and the row decoder 23 will now be discussed with referenceto FIG. 10.

The block set timing signal Bstt and the block reset timing signal Brstprovided from the timing signal generation circuit 5 to the blockselection circuit 24 are pulse signals. When the block selection circuit24 is provided with the block address signal Bad, which selects one ofthe blocks BL0-BL3 (block BL0 in FIG. 10), the block selection signalBs1 goes high if the block set timing signal Bstt goes high.

When the block selection signal Bs1 goes high and the word line setsignal generation circuit 25 receives the word line set timing signalWLstt, which is a pulse signal, the word line set signal generationcircuit 25 generates the word line set signal WLst, which is a pulsesignal.

The timing signal generation circuit 5 delays the word line set timingsignal WLstt by a predetermined time to generate the sense amp settiming signal SAstt, which is a pulse signal, and provides the timingsignal SAstt to each sense amp drive circuit 22. When the blockselection signal Bs1 is high and the sense amp set timing signal SAsttgoes high, the sense amp drive circuit 22 generates the sense amp drivesignals PSA, NSA. The sense amp drive signals PSA, NSA are provided tothe sense amps 8 in block BL0. This activates the sense amps 8. Suchstate is maintained.

When the word line address signal WLad is high and the word line setsignal WLst goes high, the row decoder 2 increases the voltage of thecorresponding word line WL. In block BL0, every eight word lines fromword line WL0 are sequentially selected and the voltage of the selectedword lines is increased.

The sense amps 8 in block BL0 are activated after a predetermined timefrom when the first word line WL0 is activated.

After completing the selection of every eight word lines in block BL0,the block address signal Bad shifts to select block BL2. In this state,when the block set timing signal Bstt goes high, the block selectionsignal Bs1 goes high in block BL2.

In this state, the word line set signal WLst goes high each time theword line set timing signal WLstt goes high. Every eight word lines aresequentially selected from word line WL0 based on the word line addresssignal WLad. The sense amp drive circuit 22 outputs the sense amp drivesignals PSA, NSA and activates the sense amps 8 in block BL2. Such stateis maintained.

When the selection of every eight lines in blocks BL0, BL2 is completedand after the selected state is maintained for a predetermined time, thesemiconductor memory device 100 receives the block address signal Bad toselect blocks BL0, BL2 based on the precharge command.

When the semiconductor memory device 100 is provided with the blockaddress signal Bad of block BL0 and the word line reset timing signalWLrst goes high, the word line reset signal WLrs in block BL0 goes high.As the word line reset signal WLrs goes high, all of the selected wordlines are inactivated.

When the sense amp reset timing signal SArst goes high, the sense ampdrive circuit 22 of block BL0 stops outputting the sense amp drivesignals PSA, NSA. This inactivates the sense amps 8.

Then, when the semiconductor memory device 100 is provided with theblock address signal Bad and the word line reset timing signal WLrstgoes high, the word line reset signal WLrs goes high in block BL2 andall of the selected word lines go low.

When the sense amp reset timing signal SArst goes high, block BL2 stopsreceiving the sense amp drive signals PSA, NSA. This inactivates thesense amps 8.

After the above operation, every eight word lines are sequentiallyselected from word line WL1 in blocks BL0, BL2 and the sense amps 8 areactivated. This operation is repeated in the same manner. When theselection of all of the word lines is completed in blocks BL0, BL2, thesame operation is repeated for blocks BL1, BL3.

FIG. 11 illustrates the selection of multiple word lines. An activecommand follows a test mode entry command. Based on the active command,every eight word lines are sequentially selected from word line WL0based on the word line address WLad and the block address signal Bad.

The sense amps 8 of block BL0 are activated subsequent to the selectionof word line WL0. When the selection of every eight word lines in blockBL0 is completed, the semiconductor memory device 100 receives the blockaddress signal Bad corresponding to block BL2. As a result, every eightword lines are selected in the same manner from word line WL0 in blockBL2 and the associated sense amps 8 are activated.

Then, when the selection of every eight word lines from word line WL0 inblocks BL0, BL2 is completed, the semiconductor memory device 100receives the block address signal Bad corresponding to blocks BL0, BL2in synchronism with the precharge command.

Subsequently, based on the block address signal Bad corresponding toblock BL0, the word lines selected in block BL0 are inactivated and thesense amps 8 associated with block BL0 are inactivated. Then, the wordlines selected in block BL2 are inactivated, and the sense amps 8associated with block BL2 are inactivated.

Such operation is repeated to select all of the word lines in blocksBL0, BL2. Afterward, the same operation is repeated in blocks BL1, BL3.

The semiconductor memory device 100 has the advantages described below.

(1) Multiple word lines of multiple blocks are simultaneously selected.This reduces the time required to conduct the multiple word line test.

(2) The activation timing and inactivation timing between the blocks areoffset while simultaneously selecting multiple word lines of multipleblocks. This prevents noise from being produced when sense amps areactivated or inactivated.

(3) The time from when a word line is selected to when a sense amp isactivated is the same in each block. Thus, the margin for amplifyingcell information is ensured for each block.

Second Embodiment

FIGS. 12 and 13 illustrate the operational timing of a semiconductormemory device 200 according to a second embodiment of the presentinvention. The circuit configuration of the semiconductor memory device200 of the second embodiment is the same as that of the semiconductormemory device 100 of the first embodiment.

The input timing of the block address signal Bad is changed in thesemiconductor memory device 200 to simultaneously select word lines inmultiple blocks, excluding the word lines that are selected first.

The operation of the block control circuit 21, the sense amp drivecircuit 22, and the row decoder 23 will now be described with referenceto FIG. 12.

In block BL0, when the block control circuit 21 is provided with theblock address signal Bad, the block set timing signal Bstt is providedto the block control circuit 21. As a result, the block selection signalBs1 goes high and the word line reset signal WLrs goes low.

Then, when the word line set timing signal WLstt goes high, the wordline set signal WLst goes high. In this state, the word line WL0 goeshigh in block BL0.

Then, in block BL2, the block address signal Bad and the block settiming signal Bstt are provided to the block control circuit 21. As aresult, the block selection signal Bs1 goes high, and the word linereset signal WLrs goes low.

Then, when the word line set timing signal WLstt goes high, the wordline set signal WLst goes high. In this state, the word line WL0 goeshigh in block BL2.

Then, the word line address signal WLad is switched to correspond to theaddress corresponding to WL8. Then, when the word line set timing signalWLstt goes high, the word line set signal WLst goes high. In this statethe word lines WL8 are simultaneously selected in blocks BL0, BL2.

Subsequently, every eight word lines are simultaneously selected inblocks BL0, BL2. When the selection of every eight word lines iscompleted, the word lines selected in block BL0 are simultaneouslyinactivated, and the sense amps 8 associated with block BL0 areinactivated.

Then, the word lines selected in block BL2 are simultaneouslyinactivated and the sense amps associated with block BL2 areinactivated. Afterward, the above operation is repeated in the samemanner to select all of the word lines in blocks BL0, BL2. Subsequently,the above operation is performed in the same manner in blocks BL1, BL3.

The semiconductor memory device 200 has the advantages described below.

Except for the word lines that are first selected, word lines of thesame address are selected at the same timing in multiple blocks. Thus,the time for conducting the multiple word line selection test is furtherreduced.

It should be apparent to those skilled in the art that the presentinvention may be embodied in many other specific forms without departingfrom the spirit or scope of the invention. Particularly, it should beunderstood that the present invention may be embodied in the followingforms.

The NAND circuits 14 e-14 h and the inverter circuit 13 h included inthe sense amp drive circuit 22 of FIG. 9 may be replaced by the circuitshown in FIG. 14. The circuit of FIG. 14 includes n-channel MOStransistors Tr5, Tr6, an inverter circuit 13 i, and a latch circuit 12c. The output signal of the latch circuit 12 c is provided to thetransistors Tr1-Tr3 and the inverter circuit 13 f of the sense amp drivecircuit 22 shown in FIG. 9.

In this case, when the sense amps are activated, the sense amp settiming signal SAstt goes high when the block selection signal Bs1 goeshigh. This causes the output signal of the latch circuit 12 c to go lowand activates the sense amp 8.

The sense amp reset timing signal SArst goes high when the word linereset signal WLrs is high. This causes the output signal of the latchcircuit 12 c to go high and inactivates the sense amp 8.

In the above embodiment, every eight word lines are selected in eachblock. However, the interval between selected word lines does not haveto be eight and may be any other number.

The number of blocks does not have to be four. Any other number ofblocks may be used. Further, the number of simultaneously selectedblocks is not limited to two.

The present examples and embodiments are to be considered asillustrative and not restrictive, and the invention is not to be limitedto the details given herein, but may be modified within the scope andequivalence of the appended claims.

What is claimed is:
 1. A method for conducting a multiple word lineselection test on a semiconductor memory device provided with aplurality of memory cell blocks, which include a first memory cell blockand a second memory cell block, each of the memory cell blocks having aplurality of memory cells and a plurality of word lines connected to thememory cells, and a plurality of sense amp groups connected to the firstand second memory cell blocks, each of the sense amp groups amplifyingcell information read from the plurality of memory cells of anassociated one of the memory cell blocks, the method comprising: a firststep for activating one of the plurality of word lines in the firstmemory cell block and activating the sense amp group associated with thefirst memory cell block after a predetermined time; a second step foractivating word lines in the first memory cell block other than the onethat has been activated in the first memory cell block; a third step foractivating one of the plurality of word lines in the second memory cellblock and activating the sense amp group associated with the secondmemory cell block after a predetermined time; and a fourth step foractivating word lines in the second memory cell block other than the onethat has been activated in the second memory cell block; wherein thefirst and second steps are followed by the third and fourth steps or thefirst and third steps are followed by the second and fourth steps.